The present invention relates generally to the field of valves. More particularly, the invention relates to a valve that automatically employs inflatable seals to reliably provide a pressure tight seal for a valve used to enable or restrict the flow of a fluid containing or consisting of particulate matter.
Valves are used to control the flow of fluids in various situations where the fluid is being transferred from one location to another such as when oil or gas is transferred to a processing plant through a pipeline. In some situations, these fluids may contain solid particulate matter that is mixed in with a gas or liquid or consist entirely of a solid, granular material such as sand or sugar that behaves somewhat like a liquid when treated in bulk. Unfortunately, the presence of particulate matter in a fluid may affect the performance and operation of a valve that is being used to control the flow of the fluid. For example, particles may become trapped between the valve member and the valve seat thereby preventing the valve member from properly sealing against the valve seat. This may result in undesirable leaking of the valve when it is closed. In addition, particulate matter trapped between the valve member and the valve seat may cause damage to the valve member and valve seat when the valve is opened and closed.
One common method of achieving closure for a full-bore open requirement when dealing with fluids containing particulate matter is to use a ball valve that has a rotatably mounted spherical component with penetrations and two or more ports. In such a ball valve, the valve rotating assembly is typically turned through 90 degrees to align the inlet and outlet ports of the ball closing member with fixed or spring-loaded metallic or elastomeric seats in the body of the valve. The closing member of the ball valve remains in sliding contact with the seat during the closing action. To obtain a pressure tight seal, this type of ball valve typically relies on the elastic properties of the seat material and seating component in combination with mechanical loading provided by a spring force or the pressure of the fluid being controlled. This mechanical loading in combination with the elastomeric seat member functions to exclude or entrap particles that may render the closure of the valve inadequate against the influence of a pressure differential across the closing member. Unfortunately, this type of ball valve suffers from a number of drawbacks. For example, the elastomeric seat members are susceptible to wear from the entrapment and movement of particulate matter passing through the valve. In addition, the mechanical loading on the seal inhibits the easy movement of the valve thereby limiting its ability to be implemented in conjunction with hand-operated valves.
Therefore, what is needed is an improved valve for handling fluids containing or consisting of particulate matter.
A preferred embodiment of the present invention is designed to address the above discussed problems with the prior art by providing an improved valve for restricting the flow of a fluid through a channel. The valve includes a gas-inflatable elastomeric valve seat and a compressed gas system for generating a supply of pressurized gas. A gas control selectively applies a flow of pressurized gas from the compressed gas system to the gas-inflatable elastomeric valve seat and vents pressurized gas from the gas-inflatable elastomeric valve seat. A primary closing member restricts the flow of the fluid in the channel by engaging with the gas-inflatable elastomeric valve seat. In an especially preferred embodiment, the primary closing member is a partial spherical, ball or hemispherical valve member.
Preferably, a hand-operated control selectively controls the gas-inflatable elastomeric valve seat and the primary closing member to control the flow of fluid through the channel. The hand-operated control is configured to control the gas control such that pressurized gas is automatically applied to the gas-inflatable elastomeric valve seat when the hand-operated control is operated to restrict the flow of fluid through the channel by engaging the gas-inflatable elastomeric valve seat with the primary closing member. The hand-operated control is further configured to control the gas control such that pressurized gas is vented from the gas-inflatable elastomeric valve seat when the hand-operated control is operated to permit the flow of fluid through the channel by disengaging the gas-inflatable elastomeric valve seat from the primary closing member. Furthermore, instrumentation may be provided for measuring and monitoring the gas pressure in the gas-inflatable elastomeric valve seat if desired. In one embodiment, a handwheel is attached to a drive shaft to allow an operator to operate the valve by turning the handwheel. The handwheel is attached to the drive shaft through worm and wheel gearing such that mechanical forces placed on the primary closing member are not transmitted to the handwheel. If necessary, a locking mechanism such as a frictional clutch or a locking pawl may be provided for locking the closing member in a desired position.
A gas control switch controls the gas control such that pressurized gas is supplied to the gas-inflatable elastomeric valve seat when the gas control switch is engaged and gas is vented from the gas-inflatable elastomeric valve seat when the gas control switch is disengaged. A compensation system is utilized that includes a cam that is operably connected to the drive shaft such that the position of the cam rotates about an axis when the drive shaft is rotated. The cam is positioned to engage the gas control switch when the primary closing member is in a closed position and disengage the gas control switch when the primary closing member is not in the closed position. A valve drive shaft is utilized to move the primary closing member between an open position and a closed position. A key and a keyway are provided that cooperate with the drive shaft and the valve drive shaft to disengage the gas control switch prior to the valve drive shaft moving the primary closing member out of the closed position.
The above discussed embodiment of the present invention provides a number of benefits over prior art valves. For example, employing an inflatable valve seat in a hand-operated valve allows the primary closing member and valve seat to form a bubble-tight seal even in the presence of particulate matter. In addition, the provision of a partially spherical primary closing member allows the valve to close through a fully static or moving column of bulk materials containing particulate matter by rotating or displacing the column of bulk material in conjunction with the movement of the closing member. The deflation of the valve seat prior to the movement of the primary closing member improves the functioning of the valve by preventing damage to the valve seat caused by movement of the primary closing member when the valve seat is inflated. Furthermore, the automatic nature of the deflation and inflation of the valve seat minimizes the likelihood of an operator error. Therefore, the above discussed embodiment is a significant improvement upon the prior art.
An embodiment of the present invention is also directed toward a method of closing and sealing a hand-operated valve used to control the flow of fluids containing or consisting of particulate matter. In accordance with the method, a closure member is moved from an open position to a closed position such that the closure member is positioned adjacent an inflatable elastomeric valve seat when it is in the closed position. The inflatable elastomeric valve seat is automatically inflated with pressurized gas by mechanically engaging a pressurized gas supply switch with a cam once the closure member is in the closed position. In a preferred embodiment, the automatic inflation of the inflatable valve seat is delayed for a predetermined period of time after the closure member is moved into the closed position to ensure that the closure member is fully in the closed position. The inflatable elasotomeric valve seat is automatically deflated by disengaging the cam from the pressurized gas supply switch and venting the pressurized gas from the inflatable elastomeric valve seat prior to moving the closure member to the open position.
Automatically inflating and deflating an inflatable elastomeric valve seat in a hand-operated valve makes the valve easier to use. In addition, the automatic inflation and deflation minimizes the possibility an operator will mistakenly forget to inflate or deflate the valve seat prior to moving the closure member and thereby damage the valve. Furthermore, the use of a cam to engage and disengage a gas supply switch is a relatively inexpensive and cost effective means of controlling a valve when compared to other traditional methods of valve control. Therefore, the above discussed embodiment of the present invention represents a substantial improvement upon the prior art.
In yet another embodiment the present invention provides a hand-operated valve for controlling the movement of a fluid that includes particulate matter through a channel. The hand-operated valve includes a partial spherical valve member having a valve drive shaft such that rotation of the valve drive shaft moves the partial spherical valve member between a closed position and an open position. A gas-inflatable elastomeric valve seat acts in conjunction with the partial spherical valve member to restrict the flow of fluid through the channel when the partial spherical valve member is in the closed position and the gas-inflatable elastomeric valve seat is inflated with compressed gas. A compressed gas supply is utilized to provide the supply of compressed gas. A gas supply activation switch selectively supplies compressed gas from the compressed gas supply to the gas-inflatable elastomeric valve seat when the gas supply activation switch is engaged and vents compressed gas from the gas-inflatable elastomeric valve seat when the gas supply activation switch is disengaged. The valve is controlled with a hand-operated wheel that is operatively connected to a worm and wheel gear. The worm and wheel gear is operatively connected to a drive shaft. A sleeve is connected to the drive shaft. The sleeve has a cam on an outer surface and a keyway on an inner surface. The cam is positioned such that it engages the gas supply activation switch when the partial spherical valve member is rotated into the closed position. A key is mounted on the valve drive shaft. The keyway is designed to receive the key mounted on the valve drive shaft such that, when the partial spherical valve member is rotated out of the closed position, the sleeve rotates and the cam disengages the gas supply activation switch before the key mounted on the valve drive shaft engages the keyway on the sleeve and rotates the valve drive shaft.
While a number of embodiments have been described above, the embodiments are exemplary, not limiting, and it should be readily understood that the invention is susceptible to a variety of modifications and configurations. Therefore, having summarized various aspects of the invention in simplified form, the invention will now be described in greater detail with reference to the following figures wherein similar reference numerals designate similar features throughout the figures.